Adjust Existing Measurement Annotations

For existing measurement annotations, when changing the measurement points (such as savePoints for CPDFPolylineAnnotation), it's necessary to refresh the measurement properties to obtain the new measurement values.

Note: You cannot remove the measurement properties by setting them to nil.

Below is an example code for modifying an existing polyline distance measurement annotation:

swift

// Get the page object where the annotation needs to be created
if let page = document?.page(at: 0) {

  // Create a polyline annotation
  var anotation = CPDFPolylineAnnotation(page: page, document: document)

   // Set the vertex of the polyline
  var pointsArray: [NSValue] = []
  let point1 = CGPoint(x: 100, y: 100)
  pointsArray.append(NSValue(cgPoint: point1))
  let point2 = CGPoint(x: 100, y: 200)
  pointsArray.append(NSValue(cgPoint: point2))
  let point3 = CGPoint(x: 200, y: 200)
  pointsArray.append(NSValue(cgPoint: point3))
  anotation?.setSavePoints(pointsArray)

  // Set the measurement properties for the polyline annotation
  var measureInfo = CPDFPerimeterMeasureInfo()
  anotation.measureInfo = measureInfo;

   // Update the appearance of the annotation to display it on the document
  page.updateAndAdd(anotation!)
  
  // Add a new vertex to the polyline
  let point4 = CGPoint(x: 200, y: 300)
  pointsArray.append(NSValue(cgPoint: point4))
  anotation?.setSavePoints(pointsArray)
  
  // Refresh the measurement properties to recalculate
  // Set MeasureInfo: This information will not be effective until it is added to the page
  anotation.measureInfo = measureInfo;
  
  // Refresh the appearance of the annotation
  anotation.updateAppearanceStream()
}

objective-c

// Get the page object where the annotation needs to be created
CPDFPage *page = [document pageAtIndex:0];

// Create a polyline annotation
CPDFPolylineAnnotation *anotation = [[CPDFPolylineAnnotation alloc] initWithPage:page document:document];

// Set the vertex of the polyline
NSMutableArray<NSValue *> *pointsArray = [NSMutableArray array];
CGPoint point1 = CGPointMake(100, 100);
[pointsArray addObject:[NSValue valueWithCGPoint:point1]];
CGPoint point2 = CGPointMake(100, 200);
[pointsArray addObject:[NSValue valueWithCGPoint:point2]];
CGPoint point3 = CGPointMake(200, 200);
[pointsArray addObject:[NSValue valueWithCGPoint:point3]];
[anotation setSavePoints:savePoints];

// Set the measurement properties for the polyline annotation
CPDFPerimeterMeasureInfo *measureInfo = [[CPDFPerimeterMeasureInfo alloc] init];
[anotation setMeasureInfo:measureInfo];

 // Update the appearance of the annotation to display it on the document
[page updateAndAddAnnotation:anotation];

// Add a new vertex to the polyline
CGPoint point4 = CGPointMake(200, 300);
[pointsArray addObject:[NSValue valueWithCGPoint:point4]];
[anotation setSavePoints:savePoints];

// Refresh the measurement properties to recalculate
// Set MeasureInfo: This information will not be effective until it is added to the page
 anotation.measureInfo = measureInfo;

// Refresh the appearance of the annotation
[anotation updateAppearanceStream];